Sound reproduction



y 1929- R. MILECZ 1,714,516

SOUND REPRODUCTION Filed Oct. 31 1925 3 Sheets-Sheet 1 NTOR . INV

f/ 1 4 A ORN EY w. A May 28, 1929. R. MILECZ SOUND REPRODUCTION Filed Oct. 31 1925 3 Sheets-Sheet 2 Patented May 28, 1929.

UNITED. STATES P 1,714,51 PATENT, orrics. I

RUDOLPH mrLnoz, or nonoxnlv, NEW JERSEY.

socivn 'nnrnonuc'rrom Application'filed October 31, 1925; see No. 65,972.

This invention relates to a method 0]": reproducing sound and :to apparatus for practicing the same. I

The primary object ofthis invention 1sto reproduce faithfully original sounds tliat have been translated into energy, either me chanical or electrical. A special object is to produce an'instrument capable of accurately responding to all the notes of the musical scale and of recreating the tonal characteristics of any voice or instrument. The system disclosed is based on the laws of dynamics, particularly on that law relating to the action of a force against-mass; v

The sensation called sound results from a succession of impulses reaching theear. If a sound could bedissected, each impulse,heard alone,wouldbe audible as a tap or knock. The louder the individual taps, the greater the volume of the resulting sound; while the more distinct the taps, the clearer the quality.

of the sound' To produce'taps having the desired qualities we must create impulses having corresponding properties. v

The ideal way'to produce a series o f'sepa; rate, distinct sound impulses is by a succession of equal hammer blows upon a nonvibratory member." Each blow will produce a single primary impulse, and since the member does not vibrate there will be'no secondary impulses to confuse the orderly procession of primary impulses. There will result a series of separate, staccato impulses of equal intensity that will be heard as a clear, pure tone.

TA vibrating member will produce aseries of impulses, but they will be of a legato, muffled, run-together character, since the vibrating member merely moves to and frofunder constantrestraint. The resultant tone will therefor'ebe muflied and run together. This defectis inherent in. any system'producing impulses by vibrating a member,"such as a diaphragm, and the resulting imperfect tone isfurther distorted by the use of an ampli tying horn, since the latter has tonal characteristics of its own which must unavoidably have some effect upon the sound passing through it. J Y 'I The present invention avoids'these faults of the known systems of sound reproduction by utilizinga series of hammer'blows, as outlined above; An au-difier" having a natural period of vibration far below the frequencies of the musical scale isused to translate the blows into impulses which are interpreted by i the ear as sound. Suitable mechanism, op-

the blows of the erated either electromagnetically or. mechanically, provides a hammering instrument for impartingblows to the audifier;

Other features of the invention will be.- come apparent in the following description, in which I have disclosed preferred embodiments by wayof illustration." i In the drawings 'Fig. 1 is a side, elevation of an electro magnetically operated reproducer with only the base portion of the audifier shown.

Fig. 2 is a planr'view of the reproducer on the plane of line 22 of Fig. 1.-

F F1g2. 3 s a cross section on the linefl3- 3 of ig. 4 is a detached View of the audifier. Fig; '5 is an enlarged plan view of the trans-' mltting tip. I

Fig. 6 is a cross sectional view of the same taken on theline 66 of Fig. 5. Fig. 7 is aside elevation or a operated reproducer.

Fig. 8 is a cross sectional view through the mechanically rotating table of the mechanically operated re roducer showing certain modifications.

*ig. 9 is Fi s. a I a ig. 10 is a diagrammatic view showing the flexure of the audifier;

Fig. 11 is a diagrammatic view illustrating the principle of mass interact-ion.

= The audifier, as shown in Fig. 4, is a bellshaped member having a tubular neck 23 connected to a flat rim 25'by flaring side walls 24. The transmitting tip 19 secured in the end of the tubular neck isladapted to receive hammering instrument; The side Walls 2 l-are'curved onsubstantiallv the arc of a circle, allowing the audifier to flex under'the force ofa blow to the position indicated in an exaggerated way by the dotted lines in Fig. 10 The curvature must as shown in Fig. 10, has been found satisfac j tory.

receives a blow the audifier does not au-j dibly vibrate, but sends .forth a sing leso'undl' impulse which is heard as a dull tap far be;

a plan view of theclamp shownin Several factors must be considered lecting the material for the audifier: The construction must be such that'when tip 119 low the range of the musical scale; {The ma terial must be sufficiently elastic topermit the walls to flex as shown in Fig. 10, and must also have the quality of returning rapidly to its normal relaxed condition, since every single blow must meet the resonator in its relaxed state. It has been foundthat the light er the specific gravity of a substance, the

more rapidly it returns to its relaxed state.

Tests have shown that paper, stiifened felt, or a substance having a similar specific gravity, meet the requirements.

The transmitting tip, shown in Figs. 5 and 6, must be rigid, so it can transmit the full force of the blow to the audifier, and must also be of light weight, as a heavy mass would absorb part of the energy of the blow. The tip is accordingly made of aluminum or similar light metal and is perforated at 21 to further reduce the weight. An upstanding flange 22 is provided for attaching the tip to the audifier.

In the mechanically operated reproducer, shown in Fig. 7, the blows are imparted to the transmitting tip by the hills of a vertically cut phonographic record 38. The turn-table 42, which is rotated by any welllrnown means, is slightly dished in the center, as shown at 46 (Fig. 8), and a rubber pad is interposed between the turn-table and the record. As a result of this structure, when nut 41 is tightened, the record is rigid- 1y clamped to the turn-table, and for thepurposes of this invention is practically integral therewith.

U The transmitting tip provided with a jeweled point 20 (Fig. 6), adapted to cooperate with the groove ol the record. The audifier is held in position by clamping the transmitting tip in the end of a lever 28 of Wood or similar light material. The opposite end of lever 28 is pivoted in a yoke 51, which latter is rigidly attached to a second yoke 39. The yoke 39 is free to swivel about post 40, but is supported vertically by having a screw-threaded connection with the post. This construction supports the audifier in an uprightposition with the transmitting tip free to swing laterally to follow the groove, with the audifier free to move vertically, and with the bell portion of the audilier' free and unconfined.

\Vhen the machine is operated, turn-table 42 rotates and each hill in the record groove imparts a blow to the" transmitting tip. The audifier is free to move vertically, so that after each blow its momentum carries it tree of the hill, and then, due to its weight, it falls back to meet the next blow. If the audifiei were a rigid member, its range 01 displacement, (the distance momentum cz..ries it from the hill), would be so great that it could not fall back in time to meet the next hill. But the side walls ot' the audifier are flexible, as pointed. out above, and part of the'lorce ol the blow is used in distorting the audifier, as shown in Fig. 10. The distortion puts the walls under a stress and calls forththe force tending to restore the walls to their normal relaxed state. This latter force may appropriately be called the force of restitution. It may .be said, then, that the flexibility of the side walls makes the reaction of the audifier more rapid (1) by reducing the range of displacement, since it absorbs part of the force of the blow, (2) by making possible the force of restitution, which adds its force to that of gravity in returning the transmit-ting tip to meet the next blow.

Since each blow on the audifier is a collision between two masses, we must consider the laws of dynamics in designing the masses to insure a proper rebound of the audifier after every impact. v Considering Fig, 11, it pivoted lever 47, which has a weight of one unit, be raised and allowed to tall against the mass 48, which has a weight of units, the lever will rebound sharply while the mass will be unaliected, due to its inertia. If the lever and mass were of the same weight, they would react equally. r

In thesound reproducer of this invention it would beundesirable to allow the turntable'to react after each impact, since such reaction would produce detrimental vibration o't'the turn-table, and would absorb part of the energy of the blow, preventing the full intensity of the impact from being transmitted to the audilier The turn-table is therefore given sulficient inertia to render it inditl'erent to the impact by giving it a mass at least fifty times that of the audifier.

In the machine shown in Fig. 7, the trans mitting tip rests directly upon the record. A modified mounting is shown in Fig.8, in which rubber sleeves 51 and 52 are inserted in the upper and lower ends, respectively, of a bore 50 formed in the endof arm 28. The transmitting tip 19 is mounted in the upper sleeve, while a stud 53 carrying the diamond point 54 is inserted in the lowersleeve. This form of mounting reduces the intensity of the blows transmitted to the audifier and hence diminishes the loudness, but at the same time gives softer tones andeliminates surface noises.

A modified form of clamp. is also shown in Fig. 8. The clamp 43 is provided with a slot 49 so that it may be readily inserted under the thumbscrew A, thusproviding a rapid and ellicient clamp.

In the form of the invention illustrated in Figs. 1 to 3, the hammering instrument? is operated electromagnetically. An electromagnet 12 is yieldingly supported on the base 10 by meansof a spring 13 and adjustable screw 14. Cooperating with the magnet is an armature in the form of a reed 15 which is formed integrally with the block 15, the block being clamped by a screw 17 to a massive pedestal 16 rising from the base. The

audifier is supported in free gravitative suspension with the transmitting tip'in contact with the reed by securing the transmitting tip in a split clamp 27 on one end of the arm 28 of wood or other light material. The opposite end of arm 28 is held-between nuts 29 on a screw rod 30 swiveled in the arms 31 of a yoke 32 which is adjustably supported by ascrew 33 on a relatively massive post 34 extending up from the base. .Terminals for the electromagnet are indicated M36, 37.

In this modification the reed, 15 is caused to'vibrate by passing an interrupted current, whose pulsations correspond to the desired sound, through the electromagnet. The vibrations of the reed 15 are imparted to the au-difier as a series of blows. gravitative suspension of the audifier, together with its flexibility, that enable it to react in such a manner as to receive a clean impact from each upward stroke of the reed. The reed is designed with a natural period of vibration of about 7000 vibrations per sec end, so as to be capable of transmitting all notes of'the musical scale without distortion. The audifier will respond properly to only a certain range of displacement. If

the range is too great, the force of restitution is ineffective; while if too small, the

reed does not gain enough mechanical'advantage to impart a sharp blow. The reed has a greater amplitude of vibration at its free end than toward confined end, and hence by moving the transmitting tip along the length of the reed, a critical point or focus can be found at which the audifier is given the optimum range of displacement; Once this focusis located the screw 33 is tightened and the instrument is permanently set. I

The machine of Fig. 1 normally rests on feet 55 and 56, but may be turned on its side and stood on feet 57 and 58. In either position the audifier is suspended in free gravitative relation. Y The reed 15 is a very stiff member and hence it is necessary to support it on a heavy mass that will not be afi'ected by vibration of the reed so that the fullforce of the blows will be transmitted to the audifier. The base 10 should therefore have a mass at least fifty times as great as that of the audifier.

Sincethe vibrations of the reed correspond 'to the vibrations of the original sound waves as carried by the electric current, it is possible to use the reed to cut a master phonograph record. This can be done by removing the audifier,and mounting a cutting point on the reed. The blank record is then rotated by any suitable mean,s,as by a turning lathe, while the vibrating reed is progressively moved across its face by any suitable feed mechanism.

It should be noted that the audifiei is in no sense a horn, and is given its bell:

It is the free shaped form merelyto give it the proper flexibility. This shape also enables to. be supported in an upright position without putting any part of its walls-under tension,

and helps to absorb all the energy ofthe blowin a single pulsation of deformation and restitution. While the auditor is shown as tubular, it could obviously be made hexagonal, square, or any equivalent shape.

The walls of the audifiei can be made of any thickness within reasonable limits, since increasing the thickness reduces fiexibiiity,

and hence reduces the force of restitution, but atthe sametime increases the weight, there by increasing the effect of gravityandcompensating for the diminished forceof restitution. 1

As stated before, a louder sound results froln louder individual taps. Louder taps can be produced by using a larger"audifier,

Which Will be heavier and hence cause more vehement impacts. Since this system is based each blow at any frequency within the musical scale. 1

I What I claim is 1. A sound repro'ducer comprising a soundsaid reed in free gravitative relation, and electromagnetic means for vlbrating said reed.

ing instrument having a tip secured thereto, a reed, said sounding instrument resting on 2. A sound reproducer comprising a sound I ing instrument having a neck portion and a bell portion, a transmittingtip carried by the neck portion, and a vibrating reed mounted to impart a series of blows to said tip.

3. A sound reproducer comprisinga sounding instrument having a neck portion and an outwardly flaring bell portion, a transmitting tip carried by the neck, portion, a pivoted lever engaged with said tip and supporting, the sounding instrument with its bell portion in free,unrestrainedrelation, and electromagnetic means for imparting a series of impacts to said tip.

4. A sound reproducer comprising a sounding instrument havingza tip secured thereto, a pivoted lever carrying saidtip, said lever being ad ustably mounted upon a base, a

reed mounted on said base in operative relation tosaid tip, and means'it'or vibrating said reed. i

5. Asound re roducer comprising a sounding instrumen raving a neck portion and a bellportion,.a transmitting tip carried by the neck portion, a pivoted lever engaged With said tip and supporting the sounding instrument With its bell portion in free, unrestrained relation, a base upon which said lever is adjusta-bly'mounted, a reed mounted on said base, said tip resting in tree gravitative relation against said reed, and electrom agnetic means for vibrating said reed.

6. A sound instrument con'iprising a reed having a naturalperiod ofvibration higher than the frequencies of the musical scale, a base supporting said reed and electromagnetic means for vibrating said reed.

7. A sound instrument comprising a reed having a'natural period of vibration higher than the frequencies of the musical scale, a relatively massive base supporting said reed, and electromagnetic means for vibrating said reed.

8. Sounding mechanism comprising a support, a tongue connected to the support at its root, a contact tip adapted to engage one side of the free end of the tongue, said tip being disjunct from the tongue, electromag netic means engaging the other side of the tongue for agitating the tongue, and a flexible reactive member connected to the tip.

In testimony whereof I aflix my signature.

RUDOLPH MILEGZ. 

